PROJECT SUMMARY/ABSTRACT Relative to Whites, Black mothers have higher odds of preterm birth (PTB) and small-for-gestational-age birth (SGA), leading to racial differences in infant mortality. Compelling evidence exists for racial discrimination and residential segregation as determinants of such adverse birth outcomes. Yet, more complete assessments of the racial social structure are needed to identify the role of additional structural factors and maternal mediating pathways. We will elucidate structural predictors of Black PTB and SGA risk by testing two Specific Aims. Aim 1: Systematically test structural predictors of unequal risk of preterm and small-for-gestational- age birth for Black mothers, and the role of maternal- and area-level mediators. Structural factors will be assessed at the county or metropolitan statistical area (MSA) using diverse public data sources and include: 1) area anti-Black prejudice from aggregated web-based measurements of bias and racism; 2) Black residential segregation as the isolation index; 3) Black socioeconomic disadvantage from a multidimensional composite; 4) neighborhood violent crime exposure and incarceration risk for Black residents; and 5) structural barriers to healthcare, measured as a) spatial access to primary care, b) availability of Black physicians, c-d) uninsurance and inadequate prenatal care rates for Black mothers, and e) availability of public health and contraceptive services. Black-White (B-W) differences in structural factors also will be examined. Using national birth records (2014-2017), the sample will include singleton births to non-Hispanic US born Black and White mothers in MSAs with at least 10,000 Black residents. Multilevel models will allow for prediction of PTB and SGA risk for Black mothers, area variance in risk, and area-specific B-W differences in risk. Mediation of structural factors by maternal- and area-level sociodemographic and health variables will be tested. Mothers with prior PTB also will be considered as structural factors may restrict access to needed health interventions for this population. Aim 2: Estimate the effect of racial societal stressors on Black preterm birth risk. Variation in timing and location of high publicity killings of Black persons, likely to be viewed as unjust or racially motivated, will be exploited to create a natural experiment. Black preterm birth risk is expected to increase after high publicity Black killings, particularly for exposure in the first four gestational months, for the most publicized killings, and in areas proximate to the killing. Due to their potential for intense media coverage, killings of Black persons will come from datasets of police-perpetrated and extremist-perpetrated killings. Number of media stories within 60-days of the killing will be used to identify high publicity killings (top decile; ~35 killings). The project will provide novel and rigorous tests of the racial social structure and racial societal stressors as predictors of unequal risk of PTB and SGA for Black mothers. By examining mediating paths and barriers to healthcare access, the project can inform health prevention efforts to improve Black birth outcomes.